CN106797295B

CN106797295B - Method and apparatus for allocating radio resources based on single resource unit in WLAN

Info

Publication number: CN106797295B
Application number: CN201580054107.7A
Authority: CN
Inventors: 崔镇洙; 赵汉奎; 李旭峰
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2014-10-05
Filing date: 2015-10-05
Publication date: 2020-07-03
Anticipated expiration: 2035-10-05
Also published as: US10098110B2; WO2016056808A1; US20170295566A1; CN106797295A

Abstract

A method and apparatus for allocating radio resources based on a single resource unit in a WLAN are disclosed. The method for allocating radio resources based on a single resource unit in a WLAN system may include the steps of: the AP schedules a plurality of wireless resources for communicating with a plurality of STAs on a bandwidth; and the AP transmitting the plurality of items of downlink data to each of the plurality of STAs through each of a plurality of wireless resources, wherein each of the plurality of wireless resources can include only at least one first resource unit or only at least one second resource unit when resource allocation based on the virtual allocation resource unit is not supported, wherein a size of the first resource unit can be larger than a size of the second resource unit.

Description

Method and apparatus for allocating radio resources based on single resource unit in WLAN

Technical Field

The present invention relates to wireless communication, and more particularly, to a method and apparatus for allocating radio resources based on a single resource unit in a WLAN (wireless local area network).

Background

Discussion of next generation Wireless Local Area Networks (WLANs) is underway. In the next generation WLAN, the purpose is 1) to improve an Institute of Electrical and Electronics Engineers (IEEE)802.11 Physical (PHY) layer and a Medium Access Control (MAC) layer in 2.4GHz and 5GHz bands, 2) to improve spectrum efficiency and area throughput, and 3) to improve performance in real indoor and outdoor environments such as an environment where an interference source exists, a dense multi-kind network environment, and an environment where a high user load exists.

An environment mainly considered in the next generation WLAN is a dense environment with many Access Points (APs) and Stations (STAs) and improvements in spectral efficiency and area throughput are discussed in the dense environment. Further, in the next generation WLAN, substantial performance improvement is focused on an outdoor environment that is not much considered in the existing WLAN, in addition to an indoor environment.

In particular, scenes such as wireless offices, smart homes, stadiums, hotspots, and buildings/rooms are mainly considered in the next-generation WLAN, and discussion about system performance improvement in a dense environment where there are many APs and STAs is made based on the corresponding scenes.

In the next generation WLAN, it is expected that improvement of system performance and outdoor environment performance in an Overlapping Basic Service Set (OBSS) environment and cellular offloading (cellular offloading) will be actively discussed, instead of improvement of single link performance in one Basic Service Set (BSS). The directivity of the next generation means that the next generation WLAN gradually has a technical range similar to that of mobile communication. When considering the situation where mobile communication and WLAN technologies have been discussed in recent years in small cells and direct-to-direct (D2D) communication areas, it is predicted that the technological and commercial convergence of next generation WLANs and mobile communication will be further active.

Disclosure of Invention

The present invention provides a method for allocating radio resources based on a single resource unit in a WLAN.

The present invention also provides a wireless communication apparatus for performing a method of allocating radio resources based on a single resource unit in a WLAN.

In one aspect, a method of allocating radio resources based on a single resource unit in a Wireless Local Area Network (WLAN) is provided. The method comprises the following steps: scheduling, by an AP (access point), each of a plurality of wireless resources for communication with a plurality of STAs (stations) on a bandwidth; and transmitting, by the AP, each of a plurality of downlink data to each of a plurality of STAs through each of a plurality of radio resources, wherein each of the plurality of radio resources includes only at least one first resource unit or at least one second resource unit when resource allocation based on a virtual allocation resource unit is not supported, wherein a size of the first resource unit is larger than a size of the second resource unit, wherein the virtual allocation resource unit is a combination of at least one first resource unit and at least one second resource unit including a plurality of data tones that can be interleaved by one interleaver.

In another aspect, an Access Point (AP) for allocating wireless resources based on a single resource unit in a Wireless Local Area Network (WLAN) is provided. The AP includes: an RF (radio frequency) unit that transmits and receives a wireless signal; and a processor operably coupled with the RF unit, wherein the processor schedules each of a plurality of radio resources for communication with a plurality of STAs (stations) over a bandwidth, wherein the processor is implemented to transmit each of a plurality of downlink data to each of the plurality of STAs through each of the plurality of radio resources, wherein each of the plurality of radio resources includes only at least one first resource unit or at least one second resource unit when resource allocation based on a virtual allocation resource unit is not supported, wherein a size of the first resource unit is larger than a size of the second resource unit, wherein the virtual allocation resource unit is a combination of at least one first resource unit and at least one second resource unit including a plurality of data tones that can be interleaved by one interleaver.

According to the present invention, when allocating radio resources for each of a plurality of STAs based on OFDMA (orthogonal frequency division multiple access), resource allocation allocated to each of the plurality of STAs can be performed using radio resource units that have been defined to be different sizes. Therefore, scheduling flexibility can be enhanced and throughput of the WLAN can be increased.

Drawings

Fig. 1 is a conceptual view illustrating the structure of a Wireless Local Area Network (WLAN).

Fig. 2 is a conceptual view illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 3 is a conceptual view illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 4 is a conceptual view illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 5 is a conceptual view illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 6 is a conceptual view illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 7 is a flowchart illustrating a method of scheduling radio resources according to an embodiment of the present invention.

Fig. 8 is a conceptual view illustrating a DL MU PPDU format according to an embodiment of the present invention.

Fig. 9 is a conceptual view illustrating transmission of a UL MU PPDU according to an embodiment of the present invention.

Fig. 10 is a block diagram illustrating a wireless device to which embodiments of the present invention are applicable.

Detailed Description

Fig. 1 is a conceptual diagram illustrating a Wireless Local Area Network (WLAN) structure.

The upper part of fig. 1 illustrates the structure of an infrastructure Basic Service Set (BSS) of Institute of Electrical and Electronics Engineers (IEEE) 802.11.

Referring to the upper half of fig. 1, the wireless LAN system may include one or more infrastructure BSSs 100 and 105 (hereinafter, referred to as BSSs). The

BSSs

100 and 105, which are a group of an AP and an STA, such as an Access Point (AP)125 and a station (STA1)100-1 that are successfully synchronized to communicate with each other, are not concepts indicating a specific area. The BSS 105 may include one or more STAs 105-1 and 105-2 that may be connected to one AP 130.

The BSS may include at least one STA, an AP providing distribution services, and a Distribution System (DS)110 connecting a plurality of APs.

The distribution system 110 may implement an Extended Service Set (ESS)140 that is extended by connecting

multiple BSSs

100 and 105. ESS 140 may be used as a term to indicate a network configured by connecting one or more APs 125 or 230 via distribution system 110. APs included in one ESS 140 may have the same Service Set Identifier (SSID).

Portal 120 may act as a bridge connecting a wireless LAN network (IEEE 802.11) and another network (e.g., 802. X).

In the BSS illustrated in the upper half of fig. 1, a network between the

APs

125 and 130 and the STAs 100-1, 105-1 and 105-2 may be implemented. However, the network is configured even between STAs without the

APs

125 and 130 to perform communication. A network that performs communication by configuring a network between STAs even without the

APs

125 and 130 is defined as a point-to-point (Ad-Hoc) network or an Independent Basic Service Set (IBSS).

The lower half of fig. 1 illustrates a conceptual diagram of IBSS.

Referring to the lower half of fig. 1, the IBSS is a BSS operating in a point-to-point mode. Since the IBSS does not include an Access Point (AP), a centralized management entity performing a management function at the center does not exist. That is, in the IBSS, the STAs 150-1, 150-2, 150-3, 155-4 and 155-5 are managed in a distributed manner. In an IBSS, STAs 150-1, 150-2, 150-3, 155-4 and 155-5 may all be made up of mobile STAs and no access to the DS is allowed to make up a self-contained network.

An STA, which is a predetermined functional medium, may be used as a meaning including all APs and non-AP Stations (STAs) including a Medium Access Control (MAC) compliant with an Institute of Electrical and Electronics Engineers (IEEE)802.11 standard and a physical layer interface for a radio medium.

A STA may be referred to by various names, such as a mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a mobile subscriber unit, or simply a user.

Hereinafter, in an embodiment of the present invention, data (alternatively, or frames) transmitted by the AP to the STA may be expressed as a term called downlink data (alternatively, downlink frames), and data transmitted by the STA to the AP may be expressed as a term called uplink data (alternatively, uplink frames). Further, transmissions from the AP to the STA may be denoted as downlink transmissions, and transmissions from the STA to the AP may be denoted as terminology referred to as uplink transmissions.

Further, a PHY Protocol Data Unit (PPDU), a frame, and data transmitted through downlink transmission may be denoted as terms such as a downlink PPDU, a downlink frame, and downlink data, respectively. The PPDU may be a data unit including a PPDU header and a physical layer service data unit (PSDU) (alternatively, a MAC Protocol Data Unit (MPDU)). The PPDU header may include a PHY header and a PHY preamble, and the PSDU (alternatively, MPDU) may include a frame or an indication frame (alternatively, an information unit of a MAC layer), or a data unit indicating the frame. The PHY header may be denoted as a Physical Layer Convergence Protocol (PLCP) header, which is another term, and the PHY preamble may be denoted as a PLCP preamble, which is another term.

Also, PPDU, frame and data transmitted through uplink transmission may be denoted as terms such as uplink PPDU, uplink frame and uplink data, respectively.

In a conventional wireless LAN system, the entire bandwidth may be used for downlink transmission to one STA and uplink transmission to one STA. Further, in the wireless LAN system to which the presently described embodiments are applied, the AP may perform Downlink (DL) multi-user (MU) transmission based on multiple input multiple output (MU MIMO), and the transmission may be expressed as a term referred to as DL MU MIMO transmission.

In the wireless LAN system according to the embodiment, a transmission method based on Orthogonal Frequency Division Multiple Access (OFDMA) is supported for uplink transmission and/or downlink transmission. Specifically, in the wireless LAN system according to the embodiment, the AP may perform DL MU transmission based on OFDMA, and the transmission may be expressed as a term referred to as DL MU OFDMA transmission. When performing DL MU OFDMA transmission, the AP may transmit downlink data (alternatively, a downlink frame and a downlink PPDU) to a plurality of respective STAs through a plurality of respective frequency resources on overlapping time resources. The plurality of frequency resources may be a plurality of sub-bands (alternatively, subchannels) or a plurality of Resource Units (RUs) (alternatively, basic tone (tone) units or small tone units). DL MU OFDMA transmission may be used with DL MU MIMO transmission. For example, DL MU MIMO transmission based on multiple space-time streams (alternatively, spatial streams) may be performed on a particular sub-band (alternatively, sub-channel) allocated for DL MU OFDMA transmission.

Further, in the wireless LAN system according to the embodiment, uplink multi-user (UL MU) transmission may be supported in which a plurality of STAs transmit data to the AP on the same time resource. Uplink transmission by multiple respective STAs on overlapping time resources may be performed on a frequency domain or a spatial domain.

When uplink transmission is performed by a plurality of corresponding STAs on a frequency domain, different frequency resources may be allocated to the plurality of corresponding STAs as uplink transmission resources based on OFDMA. The different frequency resources may be different frequency sub-bands (alternatively, sub-channels) or different Resource Units (RUs). A plurality of corresponding STAs may transmit uplink data to the AP through different frequency resources. The transmission method through the different frequency resources may be expressed as a term called UL MUOFDMA transmission method.

When uplink transmission is performed on the spatial domain by a plurality of respective STAs, different spatio-temporal streams (alternatively, spatial streams) may be allocated to the plurality of respective STAs, and the plurality of respective STAs may transmit uplink data to the AP through the different spatio-temporal streams. The transmission method through different spatial streams may be expressed as a term referred to as UL MU MIMO transmission method.

UL MU OFDMA transmissions and UL MU MIMO transmissions may be used with each other. For example, UL MU MIMO transmission based on multiple space-time streams (alternatively, spatial streams) may be performed on a particular subband (alternatively, a subchannel) allocated for UL MU OFDMA transmission.

In a legacy wireless LAN system that does not support MU OFDMA transmission, a multi-channel allocation method is used to allocate a wider bandwidth (e.g., 20MHz extra bandwidth) to one terminal. When the channel element is 20MHz, the multiple channels may include a plurality of 20MHz channels. In the multi-channel allocation method, a primary channel rule is used to allocate a wider bandwidth to a terminal. When the primary channel rule is used, there is a limit for allocating a wider bandwidth to a terminal. In particular, according to the primary channel rule, when a secondary channel adjacent to a primary channel is used in an overlapping bss (obss), and it is thus busy, STAs may use the remaining channels other than the primary channel. Accordingly, since the STA can transmit the frame only to the primary channel, the STA receives a restriction on transmission of the frame through the multi-channel. That is, in the legacy wireless LAN system, by operating a wider bandwidth in the current wireless LAN environment where OBSS is not small, the main channel rule for allocating a plurality of channels may be a large limitation in obtaining high throughput.

To solve this problem, in this embodiment, a wireless LAN system is disclosed which supports the OFDMA technique. That is, the OFDMA technique may be applied to at least one of the downlink and uplink. Also, the MU-MIMO technique may be additionally applied to at least one of a downlink and an uplink. When using OFDMA technology, multiple channels can be used simultaneously by not one terminal but multiple terminals without being limited by the main channel rules. Thus, a wider bandwidth may operate to improve the efficiency of operating the wireless resources.

An example of the time-frequency structure assumed in the wireless LAN system according to this exemplary embodiment may be as described below.

A Fast Fourier Transform (FFT) size/Inverse Fast Fourier Transform (IFFT) size may be defined as N times the FFT/IFFT size used in the legacy wireless LAN system (where N is an integer, e.g., N ═ 4). More specifically, a4 times sized FFT/IFFT may be applied to the second portion of the HE PPDU compared to the first portion of the HEPPDU. For example, 256FFT/IFFT may be applied to a 20MHz bandwidth, 512FFT/IFFT may be applied to a 40MHz bandwidth, 1024FFT/IFFT may be applied to an 80MHz bandwidth, and 2048FFT/IFFT may be applied to a contiguous 160MHz bandwidth or a non-contiguous 160MHz bandwidth.

The subcarrier spacing/interval may correspond to a size 1/N times the subcarrier spacing used in the legacy wireless LAN system (where N is an integer, e.g., 78.125kHz when N is 4).

An Inverse Discrete Fourier Transform (IDFT)/Discrete Fourier Transform (DFT) (or FFT/IFFT) -based IDFT/DFT length (or effective symbol length) may correspond to N times the IDFT/DFT length in the legacy wireless LAN system. For example, in a legacy wireless LAN system, in the case where the IDFT/DFT length is equal to 3.2 μ s and N is 4, in the wireless LAN system according to this exemplary embodiment, the IDFT/DFT length may be equal to 3.2 μ s 4(═ 12.8 μ s).

The length of the OFDM symbol may correspond to an IDFT/DFT length having a length of a Guard Interval (GI) added thereto. The length of the GI may have different values, such as 0.4. mu.s, 0.8. mu.s, 1.6. mu.s, 2.4. mu.s, and 3.2. mu.s.

When the OFDMA-based resource allocation method according to an embodiment of the present invention is used, resource allocation units defined by different sizes may be used. In particular, a Basic Tone Unit (BTU) and a Small Tone Unit (STU) may be defined for OFDMA-based resource allocation.

The AP may determine DL transmission resources and/or UL transmission resources for at least one STA based on such various resource elements. The AP may transmit at least one PPDU to at least one STA through the scheduled DL transmission resources. Further, the AP may receive at least one PPDU transmitted by at least one STA through DL transmission resources.

A BTU may be a relatively large size resource unit compared to an STU. For example, a BTU may be defined as a size of 56 tones, 114 tones, etc. Regardless of the size of the available bandwidth (e.g., 20MHz, 40MHz, 80MHz, 160MHz, etc.), the BTUs may be defined as the same size or as a size that varies depending on the size of the available bandwidth. For example, as the size of the available bandwidth increases, the size of the BTU may be defined as a relatively large value. The tone may be understood to be the same as a subcarrier.

An STU may be a relatively small size resource unit compared to a BTU. For example, an STU may be defined as a size of 26 tones.

Resource units such as BTUs and STUs may be allocated over the entire bandwidth (or available bandwidth) in view of left and right guard tones located at both ends of the entire bandwidth and used to reduce interference and Direct Current (DC) tones located at the center tone of the entire bandwidth. In addition, resource units such as BTUs and STUs may be allocated in consideration of residual tones, which may be used for user allocation separation (or resource allocation for each STA), common pilots, Automatic Gain Control (AGC), phase tracking, and the like.

In the entire bandwidth, allocation methods (the number of allocations, allocation positions, etc.) of resource units such as BTUs and STUs over the entire bandwidth may be set in consideration of resource utilization efficiency and scalability (or scalability) according to the entire bandwidth. The allocation method of the resource units such as BTUs and STUs may be predefined or signaled based on various methods (e.g., based on signaling of a signal field included in a PPDU header of a PPDU).

Hereinafter, a specific resource allocation method based on the BTU and the STU will be described.

Fig. 2 discloses BTU and STU based resource allocation for all available bandwidth.

Table 1 below discloses the basic resource allocation of BTUs and STUs over bandwidths of 20MHz, 40MHz, and 80 MHz.

< Table 1>

Referring to FIG. 2 and Table 1, BTU

May be defined as 56 tones and the STU may be defined as 26 tones. Based on the DC tone, one STU may be implemented as two divided STUs corresponding to 13 tones.

2 BTUs and 5 STUs may be allocated for a 20MHz bandwidth that includes 242 available tones. Further, 4 BTUs and 10 STUs may be allocated for a 40MHz bandwidth including 484 available tones, and 8 BTUs and 21 STUs may be allocated for an 80MHz bandwidth including 994 available tones.

One STA may be allocated 1 or 2 BTUs for a 20MHz bandwidth. Further, one STA may be allocated 1 or 2 BTUs for a 40MHz bandwidth, and 1, 2, or 4 BTUs for an 80MHz bandwidth.

1 STA may be allocated 1, 2, 4, or 5 STUs for a 20MHz bandwidth. In consideration of signaling for the number of STUs allocated to one STA, the number 5, which is the maximum number of STUs allocatable to 1 STA on a 20MHz bandwidth, may be defined as another value. Further, 1 STA may be allocated 1, 2, 4, or 10 STUs for a 40MHz bandwidth. In consideration of signaling for the number of STUs allocated to 1 STA, the number 10, which is the maximum number of STUs allocatable to 1 STA over a 40MHz bandwidth, may be defined as another value. In addition, 1, 2, 4, or 21 STUs may be allocated to one STA for an 80MHz bandwidth. The number 21, which is the maximum number allocatable to 1 STA on the 80MHz bandwidth, may be defined as another value in consideration of signaling for the number of STUs allocated to 1 STA.

According to one embodiment of the present invention, a virtual allocation resource unit including tones corresponding to a combination of at least one BTU and at least one STU may be defined, and resource allocation based on the virtual allocation resource unit may be performed. The allocation of resources based on the virtually allocated resource units may also be referred to as virtualization.

The virtual allocated resource unit may be a resource unit for reusing an interleaver size and OFDM numerology of an existing WLAN system. Further, the virtual allocation resource unit may be defined as a resource unit larger than the BTU and the STU and corresponding to a tone corresponding to a combination of at least one BTU and at least one STU. For example, the virtual allocation resource unit may be 242 tones which are a combination of 2 BTUs and 5 STUs and 484 tones which are a combination of 4 BTUs and 10 STUs.

In particular, when 242 tones corresponding to 2 BTUs and 5 STUs are allocated to one STA, the existing pilot allocation and the existing interleaver size can be utilized. Specifically, pilot tones may be allocated to 8 tones among 242 tones, and data tones may be allocated to the remaining 234 tones. Interleaving by the 234-size-based interleaver may be performed for the 234 data tones.

In this case, the data interleaving process and the pilot tone insertion process may be performed in the same manner as an existing STA, which has allocated 242 tones. That is, even when the 242 tone structure is not physically supported, one virtual 242 tone resource unit may be allocated to the STA. In this case, an interleaving process using an existing interleaver of 234 sizes and an insertion process of existing pilot tones (8 pilot tones) may be used. Such 242-tone resource units may be denoted by the term "virtual allocation resource units". The virtual resource allocation unit may be 242 tones or a multiple of 242 tones (e.g., 484, 968, etc.). Further, the size of the virtual allocation resource unit may be determined based on another interleaver size (108, 52, 24, etc.) that has been used in the existing WLAN system. Further, the virtual allocation resource unit may be defined as a resource unit larger than BTUs and STUs corresponding to tones corresponding to a combination of at least one BTU and at least one STU, and may include a plurality of data tones interleaved by a newly defined interleaver size.

Such a virtual allocated resource unit may be used for SU (single) OFDMA based transmission. Further, all BTUs and all STUs defined in each bandwidth related to one STA may be allocated for SU OFDMA-based transmission.

The maximum number of STAs that can be simultaneously allocated in the 20MHz bandwidth may be 7. Each of the maximum 7 STAs may be allocated each of 2 BTUs and 5 STUs. The maximum number of STAs for which resources can be allocated in the 40MHz bandwidth may be 14. Each of the maximum 14 STAs may be allocated each of 4 BTUs and 10 STUs. The maximum number of STAs to which resources can be allocated in 80MHz may be 29. Each of the 29 STAs may be allocated each of 8 BTUs and 21 STUs. Further, the maximum number of STAs to which resources can be allocated in the entire bandwidth may be limited to a number less than 29 (e.g., 20), and in such a case, a maximum of 19 STAs may be simultaneously allocated resources based on a combination of 8 BTUs and 21 STUs in 80 MHz.

Fig. 3 discloses a method of performing resource allocation for all available bandwidths using one tone type unit. Specifically, a method of performing resource allocation for all available bandwidths using only an STU is disclosed.

Table 2 below discloses resource allocations for STUs over 20MHz, 40MHz, and 80MH bandwidths.

< Table 2>

Referring to fig. 3 and table 2, a BTU may be defined as 56 tones, and an STU may be defined as 26 tones. When a resource consisting of only the STU is allocated to the STA, the BTU may be used only for allocation of a virtual allocation resource to the STA.

Only STUs may be allocated for a 20MHz bandwidth that includes 234 available tones. Further, 19 STUs may be allocated for a 40MHz bandwidth that includes 494 available tones, and 38 STUs may be allocated for an 80MHz bandwidth that includes 989 available tones.

Allocation of BTUs to one STA for 20MHz bandwidth may not be possible. Further, 1 STA may be allocated 2 or 4 BTUs for 40MHz, but such allocation of BTUs may be applied only when virtual allocation resource units are allocated to STAs. Likewise, 2 or 4 BTUs for an 80MHz bandwidth may be allocated to one STA, but such allocation of BTUs may be applied only when virtual allocation resource units are allocated only to STAs.

The number of STUs that can be allocated to one STA for a 20MHz bandwidth may be one of 1, 2, 3, 4, 5, 6, 7, 8, and 9, but some of these values (e.g., 3, 9, etc.) may be dispensed with for ease of signaling.

The number of STUs that can be allocated to one STA for 40MHz may be one of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19, but some of these values (e.g., 3, 19, etc.) may be dispensed with for convenience of signaling.

The number of STUs that can be allocated to one STA for 80MHz may be one of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, and 38, but some of these values (e.g., 3, 38, etc.) may be dispensed with for convenience of signaling.

The maximum number of STAs that can be simultaneously allocated resources in the 20MHz bandwidth may be 9. Each of a maximum of 9 STAs may be allocated to each of 9 STUs. The maximum number of STAs to which resources can be simultaneously allocated in 40MHz may be 19. Each of the maximum 19 STAs may be allocated each of the 19 STUs. The maximum number of STAs that can be simultaneously allocated resources in 80MHz may be 38. Each of the 38 STAs may be assigned to each of the 38 STUs. Further, the maximum number of STAs, which can be simultaneously allocated resources over the entire bandwidth in consideration of signaling overhead, may be limited to a value equal to or less than 20 (e.g., 18 or 20), and in such a case, a maximum of 18 or 20 STAs can be simultaneously allocated resources based on a combination of 38 STUs in an 80MHz bandwidth.

In a 40MHz bandwidth and 80MHz that support transmission of a relatively large amount of data, resource allocation may be performed based on the resource allocation method disclosed in fig. 2 and table 1, and in a 20MHz bandwidth that supports transmission of a relatively small amount of data, resource allocation may be performed based on the resource allocation method disclosed in fig. 3 and table 2.

Fig. 4 discloses a method of performing resource allocation for all available bandwidths using one tone type unit. Specifically, a method of performing resource allocation for all available bandwidth using only BTUs is disclosed.

Table 3 discloses resource allocation for BTUs over 20MHz, 40MHz, and 80MHz bandwidths.

< Table 3>

Referring to fig. 4 and table 3, a BTU may be defined as 56 tones, and an STU may be defined as 26 tones. When resources consisting of only BTUs are allocated to STAs, STUs may be used only to support allocation of virtual allocation resource units.

Only 4 BTUs can be allocated for a 20MHz bandwidth that includes 224 available tones. Further, 8 BTUs may be allocated for a 40MHz bandwidth comprising 448 available tones, and 17 or 18 BTUs may be allocated for an 80MHz bandwidth comprising 952 or 1008 tones.

One STA may be allocated 1, 2, 3, or 4 BTUs for a 20MHz bandwidth, but some of these values (e.g., 3) may be dispensed with for signaling convenience. One STA may be allocated 1, 2, 3, 4, 5, 6, 7, or 8 BTUs, but some of these values (e.g., 3) may be dispensed with for signaling convenience. One STA may be allocated 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 BTUs for an 80MHz bandwidth, but some of these values (e.g., 3) may be avoided for signaling convenience.

One STA may not be allocated an STU for a 20MHz bandwidth. The number of STUs that can be allocated to one STA for a 40MHz bandwidth may be 5 or 10, and the STUs may be used only for allocation of virtual allocation resource units. Further, the number of STUs that can be allocated to one STA for 80MHz may be 5 or 10, and STUs may be used only for allocation of virtual allocation resource units.

The maximum number of STAs that can be simultaneously allocated resources in 20MHz may be 4. Each of the maximum 4 STAs may be each of the 4 BTUs. The maximum number of STAs to which resources can be simultaneously allocated in 40MHz may be 8. Each of the maximum 8 STAs may be each of the 8 BTUs. The maximum number of STAs to which resources can be simultaneously allocated in 80MHz may be 17 or 18. Each of the maximum 17 or 18 STAs may be each of the 17 or 18 BTUs.

In a 20MHz bandwidth supporting transmission of a relatively small amount of data, a resource allocation method based only on the STU disclosed in fig. 3 and table 2 may be used to perform resource allocation to the STA, and in 40MHz and 80MHz bandwidths supporting transmission of a relatively large amount of data, a resource allocation method based only on the BTU disclosed in fig. 4 and table 3 may be used to perform resource allocation to the STA.

According to an embodiment of the present invention, information on whether BTU-only or STU-only resource allocation is performed may be included in a signal field (e.g., HE-SIG a/B) of a PPDU header. Further, signaling for resource allocation may be changed according to whether BTU-only or STU-only resource allocation is performed. For example, when the STU-only based resource allocation is performed for the 20MHz bandwidth, bit information indicating the resource allocation for each of the 9 STUs may be signaled. If the size of the BTU is 242 tone units or units corresponding to the 20MHz band, information indicating resource allocation may be compressed and signaled, and the information indicating resource allocation may not be separately transmitted. When BTU-only based resource allocation is performed for a 20MHz bandwidth, bit information indicating resource allocation for each of the 4 BTUs may be signaled. The STA may analyze the resource allocation information transmitted from the AP based on whether BTU-only or STU-only resource allocation is performed.

Fig. 5 is a conceptual diagram illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 5 discloses a method for increasing the total number of usable tones (available tones) over a bandwidth using a virtual allocation of resource units based on a combination of at least one BTU and at least one STU.

Referring to the left side of fig. 5, a virtual allocation resource unit of 246 tones corresponding to 2 BTUs (56 tones) and 3 STUs (26 tones) may be allocated to a 40MHz bandwidth. In the 246-tone virtual allocation resource unit, only 242 tones may be used as data tones and pilot tones, and 4 tones may be leftover tones (or residual tones). Accordingly, an interleaving process for data tones and an insertion process for existing pilot tones (8 pilot tones) using an existing 234-sized interleaver can be used for 246-tone virtual allocation resource units.

Two virtual allocated resource units of 246 tones may be allocated to 492 tones and operated over a 40MHz bandwidth. Of 512 tones corresponding to a 40MHz bandwidth, 20 remaining tones except 492 tones corresponding to virtual allocation resource units may be used as guard tones or DC (direct current) tones. The 20 remaining tones may be allocated to 11 left/right guard tones (or leftmost tone)/rightmost tone and 9 DC tones.

Further, in order to reduce the number of DC tones and mitigate interference, additional guard tones may be allocated between virtually allocated resource units or 20MHz unit bandwidths (or virtually allocated resource units).

Further, 242 tone virtual allocation resource units corresponding to 2 BTUs (56 tones) and 5 STUs (26 tones) may be allocated to the 40MHz bandwidth. That is, a virtual allocation resource unit of 246 tones may be allocated to a specific STA, and a virtual allocation resource unit of 242 tones may be allocated to another STA. Further, a 264 tone virtual allocation resource unit or a 242 tone virtual allocation resource unit may be selectively used on an available bandwidth.

Referring to the right side of fig. 5, as a specific example, with respect to all available 492 tones of a 40MHz bandwidth, a virtual allocation resource unit of 242 tones may be allocated for a first STA and a virtual allocation resource unit of 246 tones may be allocated for a second STA. In this case, in a virtual allocated resource unit of 246 tones, only 242 tones are used as data tones and pilot tones, and the remaining 4 tones (246-. For example, the leftover tones may be used as guard tones and common control signals for measurement. In addition, the remaining 4 tones may be used for a channel tracking pilot for CFO (channel frequency offset) measurement/compensation.

When a plurality of virtual allocated resource units of 246 tones are used for another bandwidth (e.g., 80MHz), the size of the remaining tones may be a multiple of 4 tones, and the remaining tones corresponding to the multiple of 4 tones may also be used for the above-described purpose.

Fig. 6 is a conceptual diagram illustrating a method of allocating radio resources according to an embodiment of the present invention.

Fig. 6 discloses a method for increasing the total number of usable tones over a bandwidth using virtual allocation of resource units based on at least one BTU and at least one STU.

Referring to the left side of fig. 6, a virtual allocation resource unit of 250 tones corresponding to 4 BTUs (56 tones) and 1 STU (26 tones) may be allocated to an 80MHz bandwidth. In the 250-tone virtual allocation resource unit, only 242 tones may be used as data tones and pilot tones, and 8 tones may be leftover tones (or residual tones). Accordingly, an interleaving process for data tones and an insertion process for existing pilot tones (8 pilot tones) using an existing 234-sized interleaver can be used for 250-tone virtual allocation resource units.

For example, 4 virtual allocated resource units of 250 tones may be allocated to 1000 tones and operated over an 80MHz bandwidth. Of 1024 tones corresponding to an 80MHz bandwidth, 24 remaining tones except for 1000 tones corresponding to virtual allocation resource units may be used as guard tones or DC (direct current) tones. The 24 remaining tones may be allocated to 11 left/right guard tones (or leftmost tone)/rightmost tone and 13 DC tones.

Further, 242 tone virtual allocation resource units corresponding to 2 BTUs (56 tones) and 5 STUs (26 tones) may be allocated to the 80MHz bandwidth. That is, a virtual allocation resource unit of 250 tones may be allocated to a specific STA and a virtual allocation resource unit of 242 tones may be allocated to another STA on an available bandwidth. Also, a virtual allocation resource unit of 250 tones or a virtual allocation resource unit of 242 tones may be used.

Referring to the right side of fig. 6, as a specific example, regarding all available 1024 tones of an 80MHz bandwidth, a virtual allocation resource unit of 250 tones may be allocated for at least one STA, and a virtual allocation resource unit of 242 tones may be allocated for at least one STA. When a virtual allocated resource unit of 250 tones is used, the remaining 8 tones (250 tones-242 tones) may be used for another purpose. For example, the remaining 8 tones may be used as guard tones or common control signals for measurement. Further, the tones may be used as channel tracking pilots for CFO (channel frequency offset) measurement/compensation.

When a plurality of virtual allocation resource units of 250 tones are used for another bandwidth (e.g., 160MHz), the size of the remaining tones may be a multiple of 8 tones, and the remaining tones corresponding to the multiple of 8 tones may also be used for the above description. For example, when four 250 tones are allocated, the size of all remaining tones may become 32 tones, which is four times as large as 8 tones, and 32 tones, which is a set of all remaining tones, may be utilized as an STU of 26 tone size for allocation to STAs.

The figures disclose a method for scheduling BTU and/or STU based wireless resources by an AP.

The AP schedules each of a plurality of wireless resources on a bandwidth for communication with a plurality of STAs (step S700).

Each of the plurality of radio resources may include only the at least one first resource unit or only the at least one second resource unit when resource allocation based on the virtual allocation resource unit is not supported. The size of the first resource unit may be larger than the size of the second resource unit. The virtual allocation resource unit may be a combination of at least one first resource unit and at least one second resource unit that include a plurality of data tones and may be interleaved by one interleaver.

According to an embodiment of the present invention, each of the plurality of wireless resources includes only at least one first resource unit when the size of the bandwidth is a first bandwidth size (e.g., 40MHz or 80MHz), and may include at least one second resource unit when the size of the bandwidth is a second bandwidth size (e.g., 20MHz) smaller than the first bandwidth size.

For example, the first resource unit may be a BTU corresponding to 56 tones, and each of the plurality of wireless resources for communicating with the plurality of STAs may include at least one first resource unit. Assuming that each of the plurality of radio resources includes at least one first resource unit, the allocation of the first resource unit according to the size of the bandwidth is as follows. When the size of the bandwidth is 20MHz, each of the plurality of wireless resources for communication with the plurality of STAs corresponds to at least one BTU among the 4 BTUs. When the size of the bandwidth is 40MHz, each of the plurality of wireless resources for communication with the plurality of STAs corresponds to at least one BTU among the 8 BTUs. When the size of the bandwidth is 80MHz, each of the plurality of wireless resources for communication with the plurality of STAs corresponds to at least one of 17 or 18 BTUs.

As another example, the second resource unit is an STU corresponding to 26 tones, and each of the plurality of wireless resources for communicating with the plurality of STAs may include only at least one second resource unit. Assuming that each of the plurality of radio resources includes only at least one second resource unit, allocation of the second resource unit according to the size of the bandwidth is as follows. When the size of the bandwidth is 20MHz, each of the plurality of radio resources corresponds to at least one STU among the 9 STUs. When the size of the bandwidth is 40MHz, each of the plurality of radio resources corresponds to at least one STU among the 19 STUs. Each of the plurality of radio resources corresponds to at least one of the 38 STUs when the size of the bandwidth is 80 MHz.

Further, as described above, the size of the virtual allocation resource unit may be one of: 242 tones corresponding to a combination of 2 BTUs and 5 STUs, 246 tones corresponding to 3 BTUs and 5 STUs, and 250 tones corresponding to a combination of 4 BTUs and 1 STU.

The AP transmits each of a plurality of downlink data to each of a plurality of STAs through each of a plurality of wireless resources (step S710).

A plurality of downlink data (or downlink PPDU) may be transmitted to each of the plurality of STAs through each of the plurality of wireless resources scheduled by step S700.

Fig. 8 is a conceptual diagram illustrating a DL MU PPDU format according to an embodiment of the present invention.

Fig. 8 discloses a DL MU PPDU format transmitted by an AP based on OFDMA according to an embodiment of the present invention.

Referring to fig. 8, a PPDU header of a DL MU PPDU may include L-STF (legacy short training field), L-LTF (legacy long training field), L-SIG (legacy signal), HE-SIGA (high efficiency signal a), HE-SIG B (high efficiency signal B), HE-STF (high efficiency short training field), HE-LTF (high efficiency long training field), and a data field (MAC payload). From the PHY header to the L-SIG, it can be divided into a legacy portion and an HE (high efficiency) portion.

L-SFT800 may include short training Orthogonal Frequency Division Multiplexing (OFDM) symbols. L-SFT800 may be used for frame detection, AGC (automatic gain control), diversity detection, and coarse frequency/time synchronization.

The L-SFT 810 may include long training Orthogonal Frequency Division Multiplexing (OFDM) symbols. The L-LTF810 may be used for fine frequency/time synchronization and channel prediction.

The L-SIG 820 may be used to transmit control information. The L-SIG 820 may include information about a data transmission rate and a data length.

The HE-SIG a 830 may include information indicating the STA to use for receiving the DL MU PPDU. For example, the HE-SIGA 830 may include information indicating an identifier of a specific STA (or AP) to receive a PPDU and a group of specific STAs. Further, when the DL MU PPDU is transmitted based on OFDMA or MIMO, the HE-SIG a 830 may include resource allocation information for reception of the DL MU PPDU by the STA.

In addition, the HE-SIG a 830 may include color bit information of BSS identification information, bandwidth information, tail bits, CRC bits, MCS (modulation and coding scheme) information of the HE-SIG B840, information on the number of symbols used for the HE-SIG B840, and CP (cyclic prefix) (or GI (guard interval)) length information.

The HE-SIG B840 may include information on a length MCS and a tail bit of a PSDU (physical layer service data unit) of each STA. In addition, the HE-SIG B840 may include information about the STA receiving the PPDU and OFDMA-based resource allocation information (or MU-MIMO information). When OFDMA-based resource allocation information (or MU-MIMO related information) is included in the HE-SIG B840, the resource allocation information may not be included in the HE-SIG a 830.

The HE-SIG a 850 or HE-SIG B860 may include resource allocation information (or virtual resource allocation information) of each of the plurality of STAs and resource allocation information such as information on whether to perform resource allocation using only BTUs or STUs.

The previous field of the HE-SIG B840 may be transmitted in duplicate in each of the different transmission resources. In the case of the HE-SIG B840, the HE-SIG B840 transmitted in some resource units (e.g., resource unit 1 and resource unit 2) is an independent field including individual information, and the HE-SIG B840 transmitted in the remaining resource units (e.g., resource unit 3 and resource unit 4) may be a format in which the HE-SIG B840 transmitted in other resources (e.g., resource unit 1 and resource unit 2) has been copied. Further, the HE-SIG B840 may be transmitted in a form encoded on all transmission resources. A field following the HE-SIG B840 may include individual information of each of a plurality of STAs receiving the PPDU.

The HE-STF 850 may be used to improve automatic gain control estimation in a MIMO (multiple input multiple output) environment or an OFDMA environment.

Specifically, the STA1 may receive HE-STF-1 transmitted from the AP through resource unit 1 and decode the data field 1 by performing synchronization, channel tracking/prediction, and AGC. Also, the STA2 may receive the HE-STF2 transmitted from the AP through the resource unit 2 and decode the data field 2 by performing synchronization, channel tracking/prediction, and AGC. The STA3 may receive the HE-STF3 transmitted from the AP through the resource unit 3 and decode the data field 3 by performing synchronization, channel tracking/prediction, and AGC. The STA4 may receive the HE-STF4 transmitted from the AP through the resource unit 4 and decode the data field 4 by performing synchronization, channel tracking/prediction, and AGC.

The HE-LTF 860 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

The IFFT sizes applied to the HE-STF 850 and fields subsequent to the HE-STF 850 may be different from the IFFT sizes applied to the fields prior to the HE-STF 850. For example, the size of the IFFT applied to the HE-STF 850 and the fields following the STF 850 may be 4 times larger than the size of the IFFT applied to the fields preceding the HE-STF 805. The STA may receive the HE-SIG a 830 and may be instructed to receive the downlink PPDU based on the HE-SIG a 830. In such a case, the STA may perform decoding based on the FFT size that has been changed from the HE-STF 850 and the fields following the HE-STF 850. In contrast, if the STA is not commanded to receive the downlink PPDU based on the HE-SIG a 830, the STA may stop decoding and set a NAV (network allocation vector). A CP (cyclic prefix) of the HE-STF 850 may have a size larger than that of another field, and during such a CP section, the STA may change an FFT size in order to perform decoding on a downlink PPDU.

An AP (access point) may allocate each of a plurality of wireless resources over an entire bandwidth for each of a plurality of STAs (stations), and may transmit a PPDU (physical protocol data unit) to each of the plurality of STAs through each of the plurality of wireless resources. Information on allocation of each of a plurality of wireless resources for each of a plurality of STAs may be included in the HE-SIG a 850 and the HE-SIG B860 as described above.

At this time, each of the plurality of radio resources may be a combination of a plurality of radio units (BTUs, STUs) defined as different sizes on the frequency axis. As described above, the resource allocation combination may be a combination of at least one resource unit that can be allocated on all available tones according to the size of the bandwidth.

Referring to fig. 9, a plurality of STAs may transmit UL MU PPDUs to an AP based on UL MU OFDMA.

L-STF 800, L-LTF 910, L-SIG 920, HE-SIG A930, and HE-SIG B940 may function as disclosed in FIG. 8. The information included in the signal fields (L-SIG 920, HE-SIG a 930, and HE-SIG B940) may be generated based on information included in the signal field of the received DL MU PPDU.

Up to HE-SIG B940, the STA1 may perform uplink transmission through the entire bandwidth and from HE-STF 950 may perform uplink transmission through the allocated bandwidth. STA1 may transmit the uplink frame based on the UL MU PPDU over the allocated bandwidth (e.g., resource unit 1). The AP may allocate uplink resources of each of the plurality of STAs based on the DL MU PPDU (e.g., HE-SIG a/B), and each of the plurality of STAs may be allocated the uplink resources and transmit an UL MU PPDU.

Referring to fig. 10, it is an STA capable of implementing the above-described embodiments and may be an AP 1000 or a STA1050 that is not an AP.

The AP 1000 includes a processor 1010, a memory 1020, and an RF (radio frequency) unit.

The RF unit 1030 may be connected to the processor 1010 and transmit/receive wireless signals.

The processor 1010 may implement the functions, processes, and/or methods set forth in this disclosure. For example, processor 1010 may be implemented to operate the operations of an AP in accordance with embodiments of the present invention. The processor may perform the operations of the AP disclosed in the embodiments of fig. 1 to 9.

For example, the processor 1010 may be implemented to schedule each of a plurality of wireless resources over a bandwidth for communication with a plurality of STAs and to transmit each of a plurality of downlink data to each of the plurality of STAs over each of the plurality of wireless resources.

When resource allocation based on the virtual allocation resource unit is not supported, each of the plurality of radio resources may include only at least one first resource unit or at least one second resource unit, a size of the first resource unit is larger than a size of the second resource unit, and the virtual allocation resource unit may be a combination of the at least one first resource unit and the at least one second resource unit including a plurality of data tones that may be interleaved by one interleaver. Here, the first resource unit may be a BTU, and the second resource unit may be an STU.

The non-AP STA1050 includes a processor 1060, a memory 1070, and an RF (radio frequency) unit 1080.

An RF unit 1080 may be connected to the processor 1060 and transmit/receive a wireless signal.

Processor 1060 can implement the functions, processes, and/or methods disclosed in the present invention. For example, processor 1060 may be implemented to operate the operations of an AP according to an embodiment of the invention. The processor may perform the operations of the STA disclosed in the embodiments of fig. 1 to 9.

For example, the processor 1060 may be implemented to decode scheduling information, receive downlink data, and transmit uplink data for BTUs and STUs or virtual allocation resource units included in the DL PPDU.

The

processor

1010 or 1060 may include an ASIC (application specific integrated circuit), another chipset, a logic circuit, a data processing device, and/or a converter for converting baseband signals and wireless signals. The

memory

1020 or 1070 may include a ROM (read only memory), a ROM (random access memory), a flash memory, a memory card, a storage medium, and/or another storage device. The

RF unit

1030 or 1080 may include one or more antennas for transmitting and/or receiving wireless signals.

When the embodiments are implemented as software, the above-described scheme may be implemented as a module for performing the above-described functions (procedures, functions, etc.). The modules may be stored in the

memory

1020 or 1070 and executed by the

processor

1010 or 1060. The

memory

1020 or 1070 may be internal or external to the

processor

1010 or 1060 or may be connected to the

processor

1010 or 1060 through various well-known means.

Claims

1. A method of allocating radio resources based on a single resource unit in a wireless local area network, WLAN, the method comprising:

scheduling, by an Access Point (AP), each of a plurality of wireless resources for communication with a plurality of Stations (STAs) over a bandwidth; and

transmitting, by the AP, each of a plurality of downlink data to each of the plurality of STAs through each of the plurality of wireless resources,

wherein each of the plurality of radio resources includes only at least one first resource unit or at least one second resource unit when resource allocation based on a virtual allocation resource unit is not supported,

wherein the size of the first resource unit is larger than the size of the second resource unit,

wherein the virtual allocation resource unit is a combination of at least one first resource unit and the at least one second resource unit including a plurality of data tones that can be interleaved by one interleaver.

2. The method of claim 1, wherein the first resource unit is a Basic Tone Unit (BTU) corresponding to 56 tones,

wherein each of the plurality of radio resources includes only the at least one first resource unit and corresponds to at least one BTU among 4 BTUs when the size of the bandwidth is 20MHz,

wherein each of the plurality of radio resources includes only the at least one first resource unit and corresponds to at least one BTU among 8 BTUs when the size of the bandwidth is 40MHz, and

wherein each of the plurality of radio resources corresponds to at least one BTU among 17 or 18 BTUs when each of the plurality of radio resources includes only the at least one first resource unit and when the size of the bandwidth is 80 MHz.

3. The method of claim 2, wherein the second resource unit is a Small Tone Unit (STU) corresponding to 26 tones,

wherein each of the plurality of radio resources includes only the at least one second resource unit and corresponds to at least one STU among 9 STUs when the size of the bandwidth is 20MHz,

wherein each of the plurality of radio resources includes only the at least one second resource unit and corresponds to at least one STU among 19 STUs when the size of the bandwidth is 40MHz, and

wherein each of the plurality of radio resources includes only the at least one second resource unit and corresponds to at least one STU among 38 STUs when the size of the bandwidth is 80 MHz.

4. The method of claim 1, wherein the first resource unit corresponds to a Basic Tone Unit (BTU) of 56 tone sizes,

wherein the second resource unit corresponds to a small tone unit STU of 26 tone sizes,

wherein the size of the virtual allocated resource unit is one of: 242 tones corresponding to a combination of 2 of the BTUs and 5 of the STUs, 246 tones corresponding to a combination of 3 of the BTUs and 3 of the STUs, or 250 tones corresponding to a combination of 4 of the BTUs and 1 of the STUs.

5. The method of claim 1, wherein each of the plurality of wireless resources includes the at least one first resource unit when the size of the bandwidth is a first bandwidth size,

wherein each of the plurality of radio resources includes only the at least one second resource unit when the size of the bandwidth is a second bandwidth size,

wherein the first bandwidth is greater than the second bandwidth size.

6. An access point, AP, for allocating wireless resources based on a single resource unit in a wireless local area network, WLAN, the AP comprising:

a Radio Frequency (RF) unit that transmits and receives a wireless signal; and

a processor operatively coupled with the RF unit,

wherein the processor schedules each of a plurality of wireless resources for communication with a plurality of Stations (STAs) on a bandwidth,

wherein the processor is implemented to transmit each of a plurality of downlink data to each of the plurality of STAs through each of the plurality of wireless resources,

7. The AP of claim 6, wherein the first resource unit is a Basic Tone Unit (BTU) corresponding to 56 tones,

8. The AP of claim 7, wherein the second resource unit is a Small Tone Unit (STU) corresponding to 26 tones,

9. The AP of claim 6, wherein the first resource unit corresponds to a Basic Tone Unit (BTU) of 56 tone sizes,

10. The AP of claim 6, wherein each of the plurality of wireless resources includes the at least one first resource unit when the size of the bandwidth is a first bandwidth size,

wherein the first bandwidth is greater than the second bandwidth size.